US4100590A - Scene-brightness-dependent control of flashbulb flash duration - Google Patents

Scene-brightness-dependent control of flashbulb flash duration Download PDF

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Publication number
US4100590A
US4100590A US05/734,988 US73498876A US4100590A US 4100590 A US4100590 A US 4100590A US 73498876 A US73498876 A US 73498876A US 4100590 A US4100590 A US 4100590A
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United States
Prior art keywords
flash
housing
flashbulb
light
controllable
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Expired - Lifetime
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US05/734,988
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English (en)
Inventor
Eduard Wagensonner
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Agfa Gevaert AG
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Agfa Gevaert AG
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B15/00—Special procedures for taking photographs; Apparatus therefor
    • G03B15/02—Illuminating scene
    • G03B15/03—Combinations of cameras with lighting apparatus; Flash units

Definitions

  • the invention relates to the problem of providing scene-brightness-dependent control of flash duration when the flash unit being employed is of the flashbulb type.
  • the control circuit includes a light sensor positioned to receive scene light, a light-measuring circuit operative for generating a signal indicative of the total of received scene light, and a threshold circuit operative for detecting when the total of received scene light has reached a predetermined value and in response to such detection terminating the flash being produced by the electronic flash lamp.
  • the present invention relates to the problem of providing such flash-duration control means for the control flashbulb flash units.
  • controllable- transparency optical unit such as a controllable-transparency ceramic optical unit.
  • the controllable-transparency optical unit forms part of the housing of the control apparatus.
  • the housing is so configured and dimensioned that it can be pushed over and onto the flashbulb flash unit.
  • the controllable-transparency optical unit occupies a position in front of the flashbulb of the flash unit.
  • the housing furthermore contains a battery, a light sensor positioned to receive scene light, a light-measuring circuit operative for determining total scene light, and a threshold circuit connected to the optical unit and operative for rednering the latter non-transparent when the total of scene light has reached a predetermined value during the course of the flash produced by the flashbulb of the flash unit.
  • the flashbulb When the flash unit is in readiness for operation, the flashbulb is fired.
  • the light radiating therefrom passes through the transparent controllable-transparency optical unit and travels to the subject to be photographed.
  • the light reflected back from the subject reaches the light sensor.
  • the light-measuring circuit after the elapse of a time interval dependent upon the brightness of the thusly reflected light, generates a signal whose value indicates a predetermined total of scene light. This value is detected by a threshold detector, which in response to such detection causes the controllable-transparency optical unit to undergo a transition into its non-transparent state. Accordingly, the duration of the flash produced by the flashbulb is automatically limited in dependence upon the light energy radiated out from the fired flashbulb and in dependence upon the distance between the flashbulb and the subject to be photographed.
  • the control apparatus of the present invention is provided with a plurality of controllable-transparency optical units disposed in a window-like arrangement on the front wall of the housing of the apparatus, arranged in correspondence to the arrangement of the flashbulbs and equal in number thereto.
  • each controllable-transparency optical unit is provided on both its front and its back side with a polarization filter.
  • the electrical conductors leading from the control circuit to the one or more controllable-transparency optical units extend within the front wall of the housing of the control apparatus.
  • a light-blocking element for example a gray wedge filter, mounted shiftably relative to the light sensor for varying the fraction of the scene light actually incident upon the light sensor.
  • An activating member coupled to the light-blocking element and manipulated from the exterior of the housing of the apparatus is provided with a calibrated scale for use in setting the position of the activating member and accordingly of the light-blocking element, for example in correspondence to the diaphragm setting of the camera with which the flash unit and control apparatus therefor are being used.
  • the control circuit is provided with additional adjusting means for adjusting the operation of the control circuit to take into account the sensitivity of the film being employed.
  • FIGS. 1 and 2 depict a first embodiment of the invention
  • FIG. 3 depicts a second embodiment of the invention.
  • numeral 1 denotes a one-piece housing configured and dimensioned so that it can be pushed into place over a flashbulb flash unit 2.
  • the housing 1 is shown pushed into place, in FIGS. 1 and 2.
  • the flashbulb flash unit 2 is provided with four flashbulbs 3, 4, 5, 6.
  • the front side 7 of the housing 1 is provided with four windows 8, 9, 10, 11 made of controllable-transparency ferroelectric ceramic material.
  • Each of the controllable-transparency optical units 8, 9, 10, 11 is provided on its front and on its back side with respective polarization filters 8a, 8b; 9a, 9b; 10a, 10b; 11a, 11b.
  • These optical units are transparent when voltate is not being applied to them and become non-transparent in response to the application of such voltage.
  • the application of voltage to the optical units 8, 9, 10, 11 can be either longitudinal (the voltage being applied to transparent electrodes located at opposite faces of the optical units) or transverse (the voltage being applied to interdigitated transparent comb-electrodes provided on only one of the two faces of the optical units).
  • the transparent electrodes of the optical units 8, 9, 10, 11 have connected to them electrical conductors 12 and 13. These conductors extend within the front side 7 of the housing of the control apparatus.
  • the conductors 12, 13 lead to a scene-brightness-dependent flash-duration control circuit comprised of a fast-responding light sensor 15 positioned behind a light window 16 and circuitry 14 including a light-measuring circuit for totalizing received light and a threshold circuit for determining when the total of scene light has reached a predetermined value and in response thereto applying a voltage to the optical units 8, 9, 10, 11.
  • the flash-duration control circuit per se, can be of any of the conventional types ordinarily used for the control of the duration of the flash produced by flash units of the type employing electronic flash lamps.
  • a light-blocking element 17 Arranged in front of the light sensor 15 is a light-blocking element 17, for example a gray wedge filter.
  • the light-blocking element 17 is mounted shiftable relative to the light sensor 15 for varying the fraction of scene light actually received by the sensor.
  • the light-blocking element 17 is coupled to an activating member 18 manipulatable from the exterior of the housing 1.
  • Activating member 18 is provided with a calibrated diaphragm-opening scale 19 for use in setting the position of the light-blocking element 17 in correspondence to the setting of the diaphragm of the camera with which the flashbulb flash unit 2 is being employed.
  • the housing 1 of the flash-duration control apparatus furthermore includes a battery 22 for energizing the automatic timing circuitry.
  • the battery 22 can be connected to and disconnected from such circuitry by means of a switch 21 activatable via a slider 20 which can be manipulated from the exterior of the housing 1.
  • Forming part of the timing circuitry is a variable resistor 24 whose wiper is adjustable from the exterior of the housing 1 utilizing an activating member 23.
  • Member 23 is provided with a calibrated film-sensitivity scale 25 for use in setting the resistor 24 to a value corresponding to the sensitivity of the film being employed.
  • the electrical components described above are located in a housing chamber 26 which is separated off from the chamber of housing 1 actually accommodating the flash unit 2.
  • the timing circuitry can be synchronized to camera operation or not. If synchronized, any means conventional in the art for that purpose can be used, i.e., so that the start of the light-measuring operation is coincident with the start of the exposure and/or with the start of the flash produced by the flashbulb. Such synchronization is well known in the context of timing circuits for flash units of the electronic flash lamp type.
  • FIG. 3 differs from that of FIGS. 1 and 2 in that the housing chamber 26 is provided with a mechanical receptacle 27 for a plug-and-socket connector 28 of a flash unit 29 of the type provided with eight flashbulbs, four on its front side and four on its back side.
  • the flash unit 29 is removed from the housing 1 of the flash-duration control apparatus and turned around so that now its not yet fired flashbulbs 34, 35, 36, 37 will face front and then flash unit 29 is reinserted into the housing 1.
  • the plug-and-socket connector 28 will again be received by the mechanical receptacle 27 of the housing 1.
  • the receptacle 27 merely serves to mechanically receive the base of the plug-and-socket connector 28. Electrical connections are not made within the receptacle 27.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Stroboscope Apparatuses (AREA)
  • Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)
US05/734,988 1975-11-06 1976-10-22 Scene-brightness-dependent control of flashbulb flash duration Expired - Lifetime US4100590A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE7535234U DE7535234U (de) 1975-11-06 1975-11-06 Steuerbare lichtschwaechungsvorrichtung fuer kolbenblitzlampen
DE7535234[U] 1975-11-06

Publications (1)

Publication Number Publication Date
US4100590A true US4100590A (en) 1978-07-11

Family

ID=6657382

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/734,988 Expired - Lifetime US4100590A (en) 1975-11-06 1976-10-22 Scene-brightness-dependent control of flashbulb flash duration

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US (1) US4100590A (de)
DE (1) DE7535234U (de)
GB (1) GB1569120A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0020918A1 (de) * 1979-06-21 1981-01-07 Rollei-Werke Franke & Heidecke GmbH + Co KG Reflektor für verschiedene Ausleuchtwinkel
US5614970A (en) * 1991-06-03 1997-03-25 Nikon Corporation Flash lighting apparatus and a camera equipped with the flash lighting apparatus
US20110203561A1 (en) * 2006-12-01 2011-08-25 Hunter's Manufacturing Company, Inc. D/B/A Tenpoint Crossbow Technologies Narrow Crossbow With Large Power Stroke
US9395606B1 (en) * 2015-08-07 2016-07-19 Geoffrey Herbert Harris External flash device for mobile devices

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3456101A (en) * 1966-03-18 1969-07-15 Prontor Werk Gauthier Gmbh Flash gun for expendable flash bulbs
US3517196A (en) * 1968-01-26 1970-06-23 Honeywell Inc Pyrotechnic device for interrupting the light output of a flash bulb
US3597044A (en) * 1968-09-03 1971-08-03 Rca Corp Electro-optic light modulator
US3783260A (en) * 1972-06-06 1974-01-01 Gte Sylvania Inc Selective actuating mechanism for percussive photoflash lamp array

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3456101A (en) * 1966-03-18 1969-07-15 Prontor Werk Gauthier Gmbh Flash gun for expendable flash bulbs
US3517196A (en) * 1968-01-26 1970-06-23 Honeywell Inc Pyrotechnic device for interrupting the light output of a flash bulb
US3597044A (en) * 1968-09-03 1971-08-03 Rca Corp Electro-optic light modulator
US3783260A (en) * 1972-06-06 1974-01-01 Gte Sylvania Inc Selective actuating mechanism for percussive photoflash lamp array

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0020918A1 (de) * 1979-06-21 1981-01-07 Rollei-Werke Franke & Heidecke GmbH + Co KG Reflektor für verschiedene Ausleuchtwinkel
US5614970A (en) * 1991-06-03 1997-03-25 Nikon Corporation Flash lighting apparatus and a camera equipped with the flash lighting apparatus
US20110203561A1 (en) * 2006-12-01 2011-08-25 Hunter's Manufacturing Company, Inc. D/B/A Tenpoint Crossbow Technologies Narrow Crossbow With Large Power Stroke
US9395606B1 (en) * 2015-08-07 2016-07-19 Geoffrey Herbert Harris External flash device for mobile devices

Also Published As

Publication number Publication date
DE7535234U (de) 1976-03-04
GB1569120A (en) 1980-06-11

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